2022 Vol. 13, No. 1
Air pollution has become an important issue, especially in Caribbean urban areas, and, particulate matter (PM) emitted by different natural and anthropogenic sources causes environmental and health issues. In this work, we studied the concentrations of PM10 and PM2.5 sources in an industrial and port urban area in the Caribbean region of Colombia. PM samples were collected within 48-h periods between April and October 2018 by using a Partisol 2000i-D sampler. Elemental geochemical characterization was performed by X-ray fluorescence (XRF) analysis. Further, ionic species and black carbon (BC) were quantified by ion chromatography and reflectance spectroscopy, respectively. Using the Positive Matrix Factorization (PMF) receptor model, the contributions of PM sources were quantified. The average concentration of PM10 was 46.6 ± 16.2 μg/m3, with high concentrations of Cl and Ca. For PM2.5, the average concentration was 12.0 ± 3.2 μg/m3, and the most abundant components were BC, S, and Cl. The receptor model identified five sources for PM10 and PM2.5. For both fractions, the contributions of marine sea spray, re-suspended soil, and vehicular traffic were observed. In addition, PM2.5 included two mixed sources were found to be fuel oil combustion with fertilizer industry emissions, and secondary aerosol sources with building construction emissions. Further, PM10 was found to also include building construction emissions with re-suspended soil, and metallurgical industry emissions. These obtained geochemical atmospheric results are important for the implementation of strategies for the continuous improvement of the air quality of the Caribbean region.
Air pollution has become a major problem in urban areas due to increasing industrialization and urbanization. In this study ambient concentrations of PM1 and metal concentrations as well as source contributions were identified and quantified by using Positive Matrix Factorization (PMF) in receptor modeling in the Metropolitan Area of Porto Alegre, Brazil. The PM1 samples were collected on PTFE filters from December 2012 to December 2014 in two sampling sites. Major ion and trace element concentrations were assessed. The average concentrations were 12.8 and 15.2 μg/m3 for Canoas and Sapucaia do Sul sites, respectively. Major ion contributions of PM1 were secondary pollutants such as sulfate and nitrate. Trace elements, especially Cu, Pb, Zn, Cd, and Ni also made important contributions which are directly associated with anthropogenic contributions. Our results show significantly higher levels in winter than in summer. Most of the PM1 and the analyzed PM species and elements originated from anthropogenic sources, especially road traffic, combustion processes and industrial activities, which are grouped in 7 major contributing sources. A back-trajectory analysis showed that the long-range transport of pollutants was not relevant in relation to the contribution to PM1 and metal concentrations. This work highlights the importance of urban planning to reduce human health exposure to traffic and industrial emissions, combined with awareness-raising actions for citizens concerning the impact of indoor sources.
Because incomplete confirmation is available concerning the influential role of atmosphere contamination on conjunctivitis, myopia, asthma, and allergic rhinitis in Brazil, the focus of the present work is to explore the possible relations among atmosphere contamination and eye problems. Rather that a case study on eye diseases, by way of questionnaires supplemented by the investigation of nanoparticles (NPs) on eyeglasses, the study examines the mechanisms in which NPs and ultra-fine particles are deposited on the glasses of children up to 10 years of age in urban and rural area. The important connection between atmosphere contaminants and individual protection equipment justifies improving indoor school properties in order could protect children's eyes, particularly in high-pollution/high-particulate areas.
Urban heat island (UHI), driving by urbanization, plays an important role in urban sustainability under climate change. However, the quantification of UHI's response to urbanization is still challenging due to the lack of robust and continuous temperature and urbanization datasets and reliable quantification methods. This study proposed a framework to quantify the response of surface UHI (SUHI) to urban expansion using the annual temperate cycle model. We built a continuous annual SUHI series at the buffer level from 2003 to 2018 in the Jing-Jin-Ji region of China using MODIS land surface temperature and imperviousness derived from Landsat. We then investigated the spatiotemporal dynamic of SUHI under urban expansion and examined the underlying mechanism. Spatially, the largest SUHI interannual variations occurred in suburban areas compared to the urban center and rural areas. Temporally, the increase in SUHI under urban expansion was more significant in daytime compare to nighttime. We found that the seasonal variation of SUHI was largely affected by the seasonal variations of vegetation in rural areas and the interannual variation was mainly attributed to urban expansion in urban areas. Additionally, urban greening led to the decrease in summer daytime SHUI in central urban areas. These findings deepen the understanding of the long-term spatiotemporal dynamic of UHI and the quantitative relationship between UHI and urban expansion, providing a scientific basis for prediction and mitigation of UHI.
Adsorption is a unit operation widely used for the tertiary treatment of the most diverse effluents, whose mechanism is based on removing recalcitrant compounds from the organic and inorganic origin. In this process, choosing a suitable adsorbent is a fundamental point. This review article focuses on the adsorbents with natural geological origin: minerals, clays, geopolymers, and even wastes resulted from mining activity. Therefore, over 450 articles and research papers were explored. These materials' main sources are described, and their characteristics, composition, and intrinsic properties are related to adsorption. Herein, we discuss the effects of several process parameters, such as pH, temperature, pollutant, and adsorbent concentration. Furthermore, equilibrium, kinetics, and thermodynamic aspects are also addressed, and relevant regeneration prospects and final disposal. Finally, some suggestions and perspectives on applying these adsorbents in wastewater treatment are presented as future trends.
The ceramics industry, resulting from developments of modern compounds, is a segment of great influence in worldwide sustainability. Artisanal ceramic factories based on wood combustion have significant risks for the creation and discharge of atmosphere nanoparticles (NPs) and ultra-fine particles (UFPs). At present, there is insufficient recognition on the influence of engineered-NPs on the atmosphere and health. Real improvements are indispensable to diminish contact with NPs. The present study demonstrates the main NPs and UFPS present in an area of intense artisanal wood-combustion ceramic manufacturing. Particulate matter was sampled for morphological, chemical, and geochemical studies by sophisticated electron microbeam microscopy, X-Ray Diffraction, and Raman spectroscopy. From NPs configuration (<10 nm) we identify nucleation. Several amorphous NPs (>10 nm) were produced around the studied artisanal ceramic factories. This study presents an indication of the recent information on population and work-related contact to NPs in the artisanal ceramic factories and their influence on health.
Deterioration of air quality due to the increase in atmospheric emissions from biomass burning (BB) is one of the major environmental problems worldwide. In this study, we estimated the contributions of BB to PM2.5 concentrations in the municipalities of Soledad and Malambo located in the Colombian Caribbean. The evaluation period ranged from February 24 to March 30, 2018, a period with a high number of BB events recorded in the surroundings of the evaluated sites. The contribution of BB to the two sampling sites was estimated using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) dispersion model with forwarding trajectories from each of the burning points identified by satellite images (n = 1089). The PM2.5 emissions were determined using the fire radiative power (FRP), obtained by remote-sensing data, and corresponded to the radiant energy released per time unit by burning vegetation. The average PM2.5 concentrations during the evaluation period were 19.91 μg/m3 for Soledad and 22.44 μg/m3 for Malambo. The average contribution of BB to these municipalities was 22.8% and 28.8%, respectively. The methodology used in this study allowed to estimate the contribution of this important source without knowledge of a previous tracer of BB, thereby increasing the use of the proposed procedure worldwide. This information would enable the implementation of effective mitigation, thereby diminishing the adverse impact of PM2.5 on the health of the population.
Air pollution has become a critical issue in urban areas, so a broad understanding of its spatiotemporal characteristics is important to develop public policies. This study analyzes the spatiotemporal variation of atmospheric particulate matter (PM10 and PM2.5) and ozone (O3) in Barranquilla, Colombia from March 2018 to June 2019 in three monitoring stations. The average concentrations observed for the Móvil, Policía, and Tres Avemarías stations, respectively, for PM10: 46.4, 51.4, and 39.7 μg/m3; for PM2.5: 16.1, 18.1, and 15.1 μg/m3 and for O3: 35.0, 26.6, and 33.6 μg/m3. The results indicated spatial and temporal variations between the stations and the pollutants evaluated. The highest PM concentrations were observed in the southern part of the city, while for ozone, higher concentrations were observed in the north. These variations are mainly associated with the influence of local sources in the environment of each site evaluated as well as the meteorological conditions and transport patterns of the study area. This study also verified the existence of differences in the concentrations of the studied pollutants between the dry and rainy seasons and the contribution of local sources as biomass burnings from the Isla Salamanca Natural Park and long-range transport of dust particles from the Sahara Desert. This study provides a scientific baseline for understanding air quality in the city, which enables policy makers to adopt efficient measures that jointly prevent and control pollution.
Epidemiological studies have suggested that inhalation exposure to indoor ambient air from coal-burning environments is causally associated with respiratory health risks. In order to explore the toxicological mechanisms behind the adverse health effects, the hemolytic activity of PM10 (particulate matter with an aerodynamic diameter of 10um or less) samples collected from homes burning coal in the recognized China “cancer village” Xuanwei were evaluated and matched against their trace elemental contents. The results demonstrated that the hemolytic activity of indoor PM10 in coal-burning environments ranged from 4.28% to 5.24%, with a clear positive dose-response relationship. Although low dose samples exhibited a reduced hemolytic activity, PM10 could have a toxic effect upon people in a coal-burning indoor environment for extended time periods. The concentrations of analyzed trace elements in PM10 samples ranged from 6966 to 12,958 ppm. Among the analyzed elements, Zn, Ti, Ni, Cu, Pb, Ba, Mn, Cr and V were found at higher concentrations and accounted for over 95% of the total elements. The concentrations of total analyzed elements in the PM10 samples revealed a significant positive correlation with PM10 hemolytic activity. Of the analyzed elements, Zn, Pb and Cs positively correlated with hemolysis, while Li, U and V negatively correlated with the hemolysis of human red blood cells (RBCs). Therefore, the heavy metal elements could be one of the main factors responsible for the hemolytic capacity of indoor PM10 in coal-burning environments.
This study evaluates the on use of crushed rocks (remineralizers) to increase soil fertility levels and which contributed to increase agricultural productivity, recovery of degraded areas, decontamination of water, and carbon sequestration. The use of these geological materials is part of the assumptions of rock technology and, indirectly, facilitates the achievement of sustainable development goals related to soil management, climate change, and the preservation of water resources. Research over the past 50 years on silicate rocks focused on soil fertility management and agricultural productivity. More recently, the combined use with microorganisms and organic correctives have shown positive results to mitigate soil degradation; to expand carbon sequestration and storage; and to contribute to the adsorption of contaminants from water and soil. In this article we show results obtained in several countries and we show that this technology can contribute to the sustainability of agriculture, as well as to reverse global warming. Although mineral nutrients are released more slowly from these types of inputs, they remain in the soil for a longer time, stimulating the soil biota. In addition, they are a technology to soluble synthetic fertilizers replace, since the few nutrients derived from such inputs not consumed by plants are lost by leaching, contaminating groundwater and water resources. In addition, conventional methods rely heavily on chemical pesticides which cause damage to soil's microfauna (responsible for the decomposition of organic matter and nutrient cycling) and the loss of organic carbon (in the form of dioxide), which is quickly dispersed in the atmosphere. Silicate rock powders are applied in natura, have long-lasting residual effects and reduce greenhouse gas emissions.
Human effects and environment impacts associated with nanoparticles generated from road traffic have recently attracted wide attention. Knowledge of the influencing variables on both number and mass of nanoparticles, sources, characteristics and limitations of advanced commercially accessible instruments for monitoring nanoparticles, are still scarce and not sufficient to make regulatory decision on solid particles smaller than 23 nm (SPN < 23 nm). Given the harmful effects of nanoparticles on human health (i. e. visibility impairment, cardiac-rhythm disturbance, heart attacks, premature death, etc.), their control and assessment seem to be an absolute priority.In this overview, we classify and analyze the existing knowledge of nanoparticles in road traffic atmosphere, recent progress, and emerging priorities in research related to these topics. The major aspects of ongoing research in this field, and a brief discussion of the main sources of atmosphere nanoparticles are presented. The subsequent section focuses on the influencing parameters of nanoparticles including climate conditions, height above the road surface and distance between source (road traffic) and sampling site. The next section provides a comprehensive summary on sampling measurement methodologies and instrumental techniques. We also review the health and environment implications associated with particle exposure. Finally, an evaluation of the state of research related to nanoparticles together with highlights for future research activities are also presented.
The Late Paleozoic–Early Mesozoic Mongol-Okhotsk Ocean extended between the Siberian and Amur–North China continents. The timing and modalities of the oceanic closure are widely discussed. It is largely accepted that the ocean closed in a scissor-like manner from southwest to northeast (in modern coordinates), though the timing of this process remains uncertain. Recent studies have shown that both western (West Transbaikalia) and eastern (Dzhagda) parts of the ocean closed almost simultaneously at the Early–Middle Jurassic boundary. However, little information on the key central part of the oceanic suture zone is available. We performed U-Pb (LA-ICP-MS) dating of detrital zircon from well-characterized stratigraphic sections of the central part of the Mongol-Okhotsk suture zone. These include the initial marine and final continental sequences of the East Transbaikalia Basin, deposited on the northern Argun-Idemeg terrane basement. We provide new stratigraphic ages for the marine and continental deposits. This revised chronostratigraphy allows assigning an age of ~165–155 Ma, to the collision-related flexure of the northern Argun-Idemeg terrane and the development of a peripheral foreland basin. This collisional process took place 5 to10 million years later than in the western and eastern parts of the ocean. We demonstrate that the northern Argun-Idemeg terrane was the last block to collide with the Siberian continent, challenging the widely supported scissor-like model of closure of the Mongol-Okhotsk Ocean. Different segments of the ocean closed independently, depending on the initial shape of the paleo continental margins.
Cratonic stabilization was a critical crustal process during the Hadean to Archean for the formation of cratons. The understanding of how and where this process took place is significant to evaluate the architecture of continents. The Singhbhum Craton of eastern India has well preserved Precambrian volcano-sedimentary sequences. The Simlipal volcano-sedimentary complex of Singhbhum Craton consists of circular bands of mafic volcanic rocks interlayered with quartzites/ shales/phyllites. In the present study, we report petrographic and geochemical characteristics of quartzites from Simlipal Complex coupled with U–Pb ages of detrital zircons and zircon geochemistry to understand the provenance and depositional conditions and its connection with the crustal stabilization in the Singhbhum Craton. The quartzites are texturally mature with sub-angular to sub-rounded quartz grains followed by feldspars embedded in a silty matrix. Based on modal compositions and major element ratios, these quartzites are categorized as quartz arenite and sub-lithic arenites. Trace element abundances normalized to Archean Upper Continental Crust (AUCC) display positive anomalies at U, Zr, Hf and negative anomalies at Nb. REE patterns are characterized by negative Eu anomalies (Eu/Eu* = 0.47–0.97) and flat HREE suggesting felsic provenance. These quartzites show depletion of LILE, enrichment of HFSE and transition metals relative to AUCC. High weathering indices such as CIA, PIA, and ICV are suggestive of moderate to intense chemical weathering. Low trace element ratios such as Th/Cr, Th/Sc, La/Sc, La/Co and Th/Co indicate a predominantly felsic source for these rocks. The overall geochemical signatures indicate passive margin deposition for these quartzites. Detrital zircons from the Simlipal quartzites yield U–Pb ages 3156 ± 31 Ma suggesting Mesoarchean crustal heritage. The trace element geochemistry of detrital zircons suggests that the zircons are magmatic in origin and possibly derived from the 3.1 Ga anorogenic granite/granitoid provenance of Singhbhum Craton. These observations collectively indicate the Mayurbhanj Granite and Singhbhum Granite (SBG-III) provenance for these quartzites, thereby tracking the stabilization of the eastern Indian Shield/Singhbhum Craton back to Mesoarchean.
Sequential Gaussian Simulation (SGSIM) as a stochastic method has been developed to avoid the smoothing effect produced in deterministic methods by generating various stochastic realizations. One of the main issues of this technique is, however, an intensive computation related to the inverse operation in solving the Kriging system, which significantly limits its application when several realizations need to be produced for uncertainty quantification. In this paper, a physics-informed machine learning (PIML) model is proposed to improve the computational efficiency of the SGSIM. To this end, only a small amount of data produced by SGSIM are used as the training dataset based on which the model can discover the spatial correlations between available data and unsampled points. To achieve this, the governing equations of the SGSIM algorithm are incorporated into our proposed network. The quality of realizations produced by the PIML model is compared for both 2D and 3D cases, visually and quantitatively. Furthermore, computational performance is evaluated on different grid sizes. Our results demonstrate that the proposed PIML model can reduce the computational time of SGSIM by several orders of magnitude while similar results can be produced in a matter of seconds.
The sub-arc mantle that experienced hydrous melting is commonly characterized by refractory geochemical compositions. Nevertheless, minor lherzolites with fertile compositions have also been reported for mantle peridotites from subduction zone. The petrogenesis and mantle source of the lherzolites are still controversial. The New Caledonia ophiolite (Peridotite Nappe) has been regarded as an allochthonous body of forearc lithosphere. This is supported by refractory compositions of its dominant mantle rocks. A few isolated lherzolitic massifs have also been observed in the northern part of New Caledonia. Those lherzolites are compositionally similar to abyssal peridotites, with negligible subduction-related modification. Here, we present new comprehensive geochemical compositions, in particular high-precision Sr-Nd-Hf isotope data, for the lherzolites. The initial 176Hf/177Hf ratios display moderate correlations with sensitive indicators for the extent of melting (i.e., olivine Fo, whole-rock Mg# and Yb contents in clinopyroxene) and whole-rock initial 187Os/188Os ratios. Some samples have ancient radiogenic Hf isotopes and unradiogenic Os isotope compositions, implying the preservation of ancient depletion signals in the lherzolites. The Nd isotope compositions, together with trace elements and mineral micro-textures, suggest that the lherzolites have been overprinted by a recent melt-rock interaction event. The high equilibrium temperatures of the studied samples have been estimated by the two-pyroxene REE thermometer, yielding temperatures of 1066–1315 °C. The lherzolites have more depleted Nd-Hf isotope compositions and higher equilibrium temperatures than the New Caledonia harzburgites. This indicates that the lherzolites may represent the residues of asthenosphere mantle trapped within the forearc region. Our studies on the New Caledonia lherzolites with ancient depletion signals suggest that ancient mantle domains in the convective mantle can be emplaced in forearc region by the upwelling of asthenosphere during the early stage of subduction initiation.
The Madurai Block in the Southern Granulite Terrane (SGT) of Peninsular India is one of the largest crustal blocks within the Neoproterozoic Gondwana assembly. This block is composed of three sub-blocks: the Neoarchean Northern Madurai block, Paleoproterozoic Central Madurai block and the dominantly Neoproterozoic Southern Madurai Block. The margins of these blocks are well-known for the occurrence of ultrahigh-temperature (UHT) granulite facies rocks mostly represented by Mg-Al metasediments. Here we report a dismembered layered mafic–ultramafic intrusion occurring in association with Mg-Al granulites from the classic locality of Ganguvarpatti in the Central Madurai Block. The major rock types of the layered intrusion include spinel orthopyroxenite, garnet-bearing gabbro, gabbro and gabbroic anorthosite showing rhythmic stratification and cumulate texture. The orthopyroxene-cordierite granulite from the associated Mg-Al layer is composed of spinel, cordierite and orthopyroxene. The pyroxene in both rock units is high-Al orthopyroxene formed under UHT metamorphic conditions. Conventional thermobarometry yields near-peak metamorphic conditions of 9.5–10 kbar pressure and a minimum temperature of 980 °C. We computed P–T pseudosections and contoured for the compositional as well as modal isopleths of the major mineral phases, which yield temperature above 1000 °C. FMAS petrogenetic grid, Al-in-orthopyroxene isopleth, conventional thermobarometry and calculated pseudosection reveal a clockwise pressure–temperature (P–T) path and near isothermal decompression. The U–Pb data on zircon grains from the layered magmatic suite indicate emplacement of the protolith at ca. 2.0 Ga and the metamorphic overgrowths yield weighted 206Pb/238U mean ages ca. 520 Ma. Monazite from the garnet-bearing gabbro and Opx-Crd granulite yielded 206Pb/238U weighted mean ages of ca. 532 Ma and 523 Ma marking the timing of metamorphism. We correlate the layered intrusion to a Paleoproterozoic suprasubduction zone setting, defining the Ganguvarpatti area as part of a collisional suture assembling the Northern and Central Madurai Blocks. The Paleoproterozoic magmatism and late Neoproterozoic-Cambrian UHT metamorphism can be linked to the tectonics of the Columbia and Gondwana supercontinents.
The oxygen fugacity () may affect the ionic conductivity of olivine under upper mantle conditions because Mg vacancies can be produced in the crystal structure by the oxidization of iron from Fe2+ to Fe3+. Here we investigated olivine ionic conductivity at 4 GPa, as a function of temperature, crystallographic orientation, and oxygen fugacity, corresponding to the topmost asthenospheric conditions. The results demonstrate that the ionic conductivity is insensitive to under relatively reduced conditions ( below Re-ReO2 buffer), whereas it has a clear -dependence under relatively oxidized conditions ( around the magnetite-hematite buffer). The ionic conduction in olivine may contribute significantly to the conductivity anomaly in the topmost asthenosphere especially at relatively oxidized conditions.
Lithosphere extension and upwelling of asthenosphere at post-collisional stage of an orogenic cycle generally induce diverse magmatism and/or associated high-temperature metamorphism. Nevertheless, the intimate coexistence of post-collisional magmatic activity and high-temperature metamorphism is rare. In this contribution, a lithological assemblage composing of diverse magmatic rocks deriving from distinct magma sources and coeval high-temperature metamorphism was identified in eastern Kunlun. Petrography, ages, mineral chemistry and whole-rock geochemistry demonstrated that those intimately coexistent diverse rocks were genetically related to post-collisional extension. The garnet-bearing mafic granulites in Jinshuikou area interior of the East Kunlun Orogenic Belt are mainly composed of garnet, orthopyroxene, and plagioclase, with peak metamorphic P–T conditions of ~ 701–756 °C and 5.6–7.0 kbar, representing a granulite-facies metamorphism at 409.7 ± 1.7 Ma. The diverse contemporaneous magmatic rocks including hornblendites, gabbros and granites yield zircon U–Pb ages of 408.6 ± 2.5 Ma, 413.4 ± 4.6 Ma, and 387–407 Ma, respectively. The hornblendites show N-MORB-like REE patterns with (La/Sm)N values of 0.85–0.94. They have positive zircon εHf(t) values of 0.1–4.9 and whole-rock εNd(t) values of 3.9–4.7 but relatively high (87Sr/86Sr)i values of 0.7081 to 0.7088. These features demonstrate that the hornblendites derived from a depleted asthenospheric mantle source with minor continental crustal materials in source. As for the gabbros, they exhibit arc-like elemental signatures, low zircon εHf(t) values (−4.3 to 2.5) and variable whole-rock εNd(t) values (−4.9 to 1.2) as well as high (87Sr/86Sr)i values (0.7068 to 0.7126), arguing for that they were originated from partial melting of heterogeneous lithospheric mantle anteriorly metasomatized by subducted-sediment released melts. Geochemistry of the granites defines their strongly peraluminous S-type signatures. Zircons from the granites yield a large range of εHf(t) values ranging from −30.8 to −5.1, while the whole-rock samples yield consistent (87Sr/86Sr)i values (0.7301 to 0.7342) and negative εNd(t) values (−10.1 to −12.4). These features indicate that the S-type granites could be generated by reworking of an ancient crust. Taken together, the penecontemporaneous magmatism and metamorphic event, demonstrated the early-middle Devonian transition from crustal thickening to extensional collapse. The post-collisional mantle-derived magmas serve as an essential driving force for the high-temperature granulite-facies metamorphism and anataxis of the crust associated with formation of S-type granite. This study not only constructs a more detail Proto-Tethys evolution process of the eastern Kunlun, but also sheds new light on better understanding the intimate relationship between magmatism and metamorphism during post-collisional extensional collapse.
Lumbini is a world heritage site located in the southern plains region of Nepal, and is regarded as a potential site for evaluating transboundary air pollution due to its proximity to the border with India. In this study, 82 aerosol samples were collected between April 2013 and July 2014 to investigate the levels of particulate-bound mercury (PBM) and the corresponding seasonality, sources, and influencing factors. The PBM concentration in total suspended particulate (TSP) matter ranged from 6.8 pg m−3 to 351.7 pg m−3 (mean of 99.7 ± 92.6 pg m−3), which exceeded the ranges reported for remote and rural sites worldwide. The Hg content (PBM/TSP) ranged from 68.2 ng g−1 to 1744.8 ng g−1 (mean of 446.9 ± 312.7 ng g−1), indicating anthropogenic enrichment. The PBM levels were higher in the dry season (i.e., winter and the pre-monsoon period) than in the wet season (i.e., the monsoon period). In addition, the δ202Hg signature indicated that waste/coal burning and traffic were the major sources of Hg in Lumbini during the pre-monsoon period. Meanwhile, precipitation occurring during photochemical processes in the atmosphere may have been responsible for the observed Δ199Hg values in the aerosol samples obtained during the monsoon period. The PBM concentration was influenced mostly by the resuspension of polluted dust during dry periods and crop residue burning during the post-monsoon period. The estimated PBM deposition flux at Lumbini was 15.7 μg m−2 yr−1. This study provides a reference dataset of atmospheric PBM over a year, which can be useful for understanding the geochemical cycling of Hg in this region of limited data.
The early Albian Oceanic Anoxic Event 1b (OAE 1b) is well documented in the Tethys, Pacific and North Atlantic, but few studies have evaluated whether or not terrestrial records of OAE 1b exist. In order to identify terrestrial records of the early Albian OAE 1b and to infer possible driving mechanisms, an integrated multi-proxy study from the late Aptian to Albian in the Fuxin lacustrine basin was conducted, including thick, organic-rich black mudstones, total organic carbon (TOC), organic carbon isotopes (δ13Corg), mercury concentration (Hg) and results from pyrolysis analyses (S2, Tmax and HI). Results show three distinct short-term negative δ13Corg excursions corresponding with relatively high TOC values, which could be counterparts of the Kilian, Paquier and Leenhardt sub-events of the early Albian OAE 1b. Atmospheric CO2 concentration (pCO2) recovered from C3 plant δ13Corg compositions indicates an increasing trend in Unit C during the early Albian, and there are three short-term increases of pCO2 corresponding to the three sub-events of OAE 1b at this time interval. We infer that a trend of increasing pCO2 during the Kilian sub-event in the study area is closely related to volcanism. Continental weathering calculated using chemical weathering indices (CIA, WIP and MIA(O)) show an increasing trend during the OAE 1b interval, likely resulting from warmer and more humid conditions. Mixed sources of terrestrial plants and lacustrine plankton demonstrated by pyrolysis analyses (HI vs. Tmax and S2 vs. TOC), indicate a terrestrial contribution to the organic-rich sediments of the Kilian, Paquier and Leenhardt sub-events of OAE 1b. We suggest that a CO2-forced greenhouse effect during the early Albian might have triggered the relatively warm and humid palaeoclimatic conditions, and intensified chemical weathering that combined to create high nutrient and organic matter levels that were flushed into lakes contributing to eutrophication and anoxia in lacustrine and in contemporaneous oceanic systems.
In this study, the concentration and spatial distribution of potentially toxic metals (PTMs), including arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb), copper (Cu), iron (Fe), manganese (Mn), and magnesium (Mg) in 23 wells and drinking groundwater distribution networks of Rafsanjan, located in southeast Iran were evaluated. Moreover, the assessment of carcinogenic and non-carcinogenic risks was estimated by Monte Carlo simulation (MCS). The results showed that the concentrations of As and Pb in more than 99% and 23.46% of the study area, respectively, were higher than the maximum concentration level (10 µg/L). The mean concentration of other metals, including Cd, Cr, Cu, Fe, Mg, and Mn in all drinking water resources was within the WHO standard level. The mean hazard quotient (HQ) for As in the age group of children was 9.246 and adults 2.972, indicating high non-carcinogenic risk of As in the study area. The lifetime cancer risk (LTCR) of As was 1.36E−3 for adults and 1.52E−2 for children, indicating high non-carcinogenic risk of As. The level of HQ and LTCR for Pb in both age groups was in the acceptable range. The results of sensitivity analysis showed that the most effective variables were pollutant concentration and body weight (BW), respectively. Finally, it can be concluded that exposure to PTMs, especially As through drinking water in the study area can have significant effects on people’s health living in the area; therefore, it is necessary to treat and remove As from groundwater resources before drinking or using for domestic purpose.
Cracks are accounted as the most destructive discontinuity in rock, soil, and concrete. Enhancing our knowledge from their properties such as crack distribution, density, and/or aspect ratio is crucial in geo-systems. The most well-known mechanical parameter for such an evaluation is wave velocity through which one can qualitatively or quantitatively characterize the porous media. In small scales, such information is obtained using the ultrasonic pulse velocity (UPV) technique as a non-destructive test. In large-scale geo-systems, however, it is inverted from seismic data. In this paper, we take advantage of the recent advancements in machine learning (ML) for analyzing wave signals and predict rock properties such as crack density (CD) – the number of cracks per unit volume. To this end, we designed numerical models with different CDs and, using the rotated staggered finite-difference grid (RSG) technique, simulated wave propagation. Two ML networks, namely Convolutional Neural Networks (CNN) and Long Short-Term Memory (LSTM), are then used to predict CD values. Results show that, by selecting an optimum value for wavelength to crack length ratio, the accuracy of predictions of test data can reach R2 > 96% with mean square error (MSE) < 25e-4 (normalized values). Overall, we found that: (i) performance of both CNN and LSTM is highly promising, (ii) accuracy of the transmitted signals is slightly higher than the reflected signals, (iii) accuracy of 2D signals is marginally higher than 1D signals, (iv) accuracy of horizontal and vertical component signals are comparable, (v) accuracy of coda signals is less when the whole signals are used. Our results, thus, reveal that the ML methods can provide rapid solutions and estimations for crack density, without the necessity of further modeling.
The Zhuxi deposit is a recently discovered W–Cu deposit located in the Jiangnan porphyry–skarn W belt in South China. The deposit has a resource of 3.44 million tonnes of WO3, making it the largest on Earth, however its origin and the evolution of its magmatic–hydrothermal system remain unclear, largely because alteration–mineralization types in this giant deposit have been less well-studied, apart from a study of the calcic skarn orebodies. The different types of mineralization can be classified into magnesian skarn, calcic skarn, and scheelite–quartz–muscovite (SQM) vein types. Field investigations and mineralogical analyses show that the magnesian skarn hosted by dolomitic limestone is characterized by garnet of the grossular–pyralspite (pyrope, almandine, and spessartine) series, diopside, serpentine, and Mg-rich chlorite. The calcic skarn hosted by limestone is characterized by garnet of the grossular–andradite series, hedenbergite, wollastonite, epidote, and Fe-rich chlorite. The SQM veins host high-grade W–Cu mineralization and have overprinted the magnesian and calcic skarn orebodies. Scheelite is intergrown with hydrous silicates in the retrograde skarn, or occurs with quartz, chalcopyrite, sulfide minerals, fluorite, and muscovite in the SQM veins.Fluid inclusion investigations of the gangue and ore minerals revealed the evolution of the ore-forming fluids, which involved: (1) melt and coexisting high–moderate-salinity, high-temperature, high-pressure (>450 °C and >1.68 kbar), methane-bearing aqueous fluids that were trapped in prograde skarn minerals; (2) moderate–low-salinity, moderate-temperature, moderate-pressure (~210–300 °C and ~0.64 kbar), methane-rich aqueous fluids that formed the retrograde skarn-type W orebodies; (3) low-salinity, moderate–low-temperature, moderate-pressure (~150–240 °C and ~0.56 kbar), methane-rich aqueous fluids that formed the quartz–sulfide Cu(–W) orebodies in skarn; (4) moderate–low-salinity, moderate-temperature, low-pressure (~150–250 °C and ~0.34 kbar) alkanes-dominated aqueous fluids in the SQM vein stage, which led to the formation of high-grade W–Cu orebodies. The S–Pb isotopic compositions of the sulfides suggest that the ore-forming materials were mainly derived from magma generated by crustal anatexis, with minor addition of a mantle component. The H–O isotopic compositions of quartz and scheelite indicate that the ore-forming fluids originated mainly from magmatic water with later addition of meteoric water. The C–O isotopic compositions of calcite indicate that the ore-forming fluid was originally derived from granitic magma, and then mixed with reduced fluid exsolved from local carbonate strata. Depressurization and resultant fluid boiling were key to precipitation of W in the retrograde skarn stage. Mixing of residual fluid with meteoric water led to a decrease in fluid salinity and Cu(–W) mineralization in the quartz–sulfide stage in skarn. The high-grade W–Cu mineralization in the SQM veins formed by multiple mechanisms, including fracturing, and fluid immiscibility, boiling, and mixing.
This paper presents a confidence ellipse-based method to evaluate the similarity of soil parametric data using the database from the site investigation reports. Then, the obtained similarity assessment results of parametric data are used to further estimate the site similarity via two proposed strategies, namely the mean and weighted mean approaches. The former referred to the average of parametric data similarity degrees, while the latter was the weighted average, and the weight was calculated using the coefficient of variation (COV) of each parameter. For illustration, the liquidity index (LI) dataset was firstly used to explore the performance of the presented method in the evaluation of parametric data similarity. Subsequently, the site similarity was assessed and the effects of numbers and weights of selected parameters for study were systematically studied. Lastly, the transformation models about the relationships between Cc and ω as well as between Cc and e0 were constructed to illustrate the application of the similarity analysis in reduction of transformation uncertainty. Results show that the greatest site similarity degree is at about 0.76 in this study, and the maximum decrease of transformation uncertainty can reach up to 18% and 25.5% as union parametric data similarity degree increases. Moreover, the site similarity degree represents the whole similarity between two different sites, and the presented union parameter similarity degree maintains a good agreement with transformation uncertainty.
We present major and trace element compositions of mineral concentrates comprising garnet xenocrysts, ilmenite, phlogopite, spinel, zircon, and uncommon minerals (titanite, calzirtite, anatase, baddeleyite and pyrochlore) of a newly discovered Late Cretaceous kimberlite (U-Pb zircon age 90.0 ± 1.3 Ma; 2σ) named Osvaldo França 1, located in the Alto Paranaíba Igneous Province (APIP), southeastern Brazil. Pyrope grains are lherzolitic (Lherz-1, Lherz-2 and Lherz-3), harzburgitic (Harz-3) and wehrlitic (Wehr-2). The pyrope xenocrysts cover a wide mantle column in the subcratonic lithosphere (66–143 km; 20–43 kbar) at relatively low temperatures (811–875 °C). The shallowest part of this mantle is represented by Lherz-1 pyropes (20–32 kbar), which have low-Cr (Cr2O3 = 1.74–6.89 wt.%) and fractionated middle to heavy rare earth elements (MREE-HREE) pattern. The deepest samples are represented by Lherz-2, Lherz-3, Harz-3, and Wehr-2 pyropes (36–43 kbar). They contain high-Cr contents (Cr2O3 = 7.36–11.19 wt.%) and are characterized by sinusoidal (Lherz-2 and Wehr-2) and spoon-like (Lherz-3 and Harz-3) REE patterns. According to their REE and trace elements, pyrope xenocrysts have enriched nature (e.g., Ce and Yb vs. Cr2O3), indicating that the cratonic lithosphere has been affected by a silicate melt with subalkaline/tholeiite composition due to their low Zr, Ti and Y concentrations. Besides minerals with typical kimberlitic signatures, such as ilmenite and zircon, the exotic compositions of phlogopite and ulvöspinel suggest an enriched component in the magma source. The formation of rare mineral phases with strong enrichment of light-REE (LREE) and high field strength elements (HFSE) is attributed to the late-stage kimberlitic melt. We propose a tectonic model where a thermal anomaly, represented by the low-velocity seismic anomaly observed in P-wave seismic tomography images, supplied heat to activate the alkaline magmatism from a metasomatized cratonic mantle source during the late-stages of Gondwana fragmentation and consequent South Atlantic Ocean opening. The metasomatism recorded by mineral phases is a product of long-lived recycling of subducted oceanic plates since the Neoproterozoic (Brasiliano Orogeny) or even older collisional events, contributing to the exotic character of the Osvaldo França 1 kimberlite, as well as to the cratonic lithospheric mantle.
The Duolong mineral district in western Tibet is one of the largest porphyry Cu–Au deposit fields with significant metallogenic potential in China. Its tectonic environment relevant to Early Cretaceous Cu–Au mineralization remains controversial. Here we report new whole-rock major and trace element, and Sr-Nd-Hf-Pb isotopic data for the newly discovered basalt in the Nadun area, Duolong mineral district, to decipher their genesis and further constrain the tectonic environment. A contemporaneous rhyolite sample interbedded with the basalt in the lower part of the volcanic section in the Nadun area yields an LA-ICP-MS zircon U–Pb age of 122.5 ± 1.2 Ma. The basalt samples exhibit high-K calc-alkaline/shoshonite properties and are enriched in high field strength elements, e.g., high TiO2 (1.43–1.79 wt.%) and Nb (14.6–19.5 ppm) contents, with high Nb/La ratios (0.4–0.6), which are compositionally comparable to those of Nb-enriched arc basalts (NEABs). The (87Sr/86Sr)i ratios of 0.7052 to 0.7056, negative εNd(t) (− 0.7 to − 0.2) and εHf(t) values (+ 6.0 to + 6.5), and high (206Pb/204Pb)i, (207Pb/204Pb)i, (208Pb/204Pb)i and ratios (18.522 to 18.561, 15.641 to 15.645 and 38.679 to 38.730, respectively) suggest that the Nadun NEABs are more enriched than those of the island arc basalts (IABs) in the area. The slightly enriched radiogenic isotopes for the Nadun NEABs indicate that the subducting sediments play an important role in the source. Furthermore, their high Nb, Ti, and Cu contents indicate that the source mantle wedge was metasomatized by slab melts. The Nadun NEAB and other coeval magmatic rocks in the Duolong mineral district, including adakite, OIB-like basalt, MORB-type basalt, A-type rhyolite, and common IAB, are typical rock assemblages of ridge subduction. We infer that the Duolong mineral district were formed by ridge subduction in the Early Cretaceous.
Ground-level ozone (O3) is a primary air pollutant, which can greatly harm human health and ecosystems. At present, data fusion frameworks only provided ground-level O3 concentrations at coarse spatial (e.g., 10 km) or temporal (e.g., daily) resolutions. As photochemical pollution continues increasing over China in the last few years, a high-spatial–temporal-resolution product is required to enhance the comprehension of ground-level O3 formation mechanisms. To address this issue, our study creatively explores a brand-new framework for estimating hourly 2-km ground-level O3 concentrations across China (except Xinjiang and Tibet) using the brightness temperature at multiple thermal infrared bands. Considering the spatial heterogeneity of ground-level O3, a novel Self-adaptive Geospatially Local scheme based on Categorical boosting (SGLboost) is developed to train the estimation models. Validation results show that SGLboost performs well in the study area, with the R2s/RMSEs of 0.85/19.041 μg/m3 and 0.72/25.112 μg/m3 for the space-based cross-validation (CV) (2017–2019) and historical space-based CV (2019), respectively. Meanwhile, SGLboost achieves distinctly better metrics than those of some widely used machine learning methods, such as eXtreme Gradient boosting and Random Forest. Compared to recent related works over China, the performance of SGLboost is also more desired. Regarding the spatial distribution, the estimated results present continuous spatial patterns without a significantly partitioned boundary effect. In addition, accurate hourly and seasonal variations of ground-level O3 concentrations can be observed in the estimated results over the study area. It is believed that the hourly 2-km results estimated by SGLboost will help further understand the formation mechanisms of ground-level O3 in China.
The Marwar Supergroup (NW Peninsular India) is thought to be of Ediacaran-Cambrian age, based on previous paleontological and geochronological studies. However, direct constraints on the onset of sedimentation within the Marwar basin are still scarce. In this study, we report U–Pb zircon, LA-ICP-MS, and SIMS ages from the Chhoti Khatu felsic volcanic rocks, interlayered with the Jodhpur Group sandstones (Lower Marwar Supergroup). The cathodoluminescence images of the zircons indicate complex morphologies, and core-rim textures coupled with the wide range of ages indicate that they are likely inherited or in the case of thin poorly indurated ash-beds, detrital in origin. The age spectra of 68 zircon analyses from our sampling display a dominant 800–900 Ma age peak corresponding to the age of basement “Erinpura granite” rocks in the region. The youngest inherited zircon from a felsic ash layer yielded a U–Pb age of 651 Ma ± 18 Ma that, together with previous studies and paleontological evidence, indicates a post-Cryogenian age for the initiation of Marwar sedimentation following a ~125 Ma hiatus between the end of Malani magmatism and Marwar deposition.
Glaciological mass balance (MB) is considered the most direct, undelayed and unfiltered response of the glaciers to climatic perturbations. However, it may inherit errors associated with stake under-representation, averaging over the entire glacier and human bias. Therefore, proper validation of glaciological MB with geodetic MB is highly recommended by the World Glacier Monitoring Service (WGMS). The present study focuses on the Dokriani Glacier, central Himalaya which is one of the bench-mark glaciers in the region and has glaciological MB records from 1993 to 2013 with intermittent gaps. In the present study, firstly the glaciological MB series is extended to 2014 i.e., field-based MB for one more year is computed and, to compare with it, the geodetic MB is computed for the 1999–2014 period using high resolution Cartosat-1 digital elevation model (DEM) and SRTM DEM. Finally, the study assesses the regional representation of the Dokriani Glacier in terms of MB and evaluates the influence of the MB regime on its morphological evolution. Results show that the average glaciological MB (−0.34 ± 0.2 m water equivalent (w.e.) y−1) is more negative than the geodetic MB (−0.23 ± 0.1 m w.e. y−1) for the 1999–2014 period. This is likely because of the partial representation of glacier margins in the glaciological MB, where melting is strikingly low owing to thick debris cover (>30 cm). In contrast, geodetic MB considers all marginal pixels leading to a comparatively low MB. A comparative assessment shows that the MB of Dokriani Glacier is less negative (possibly due to its huge accumulation area) than most other glacier-specific and regional MBs, restricting it to be a representative glacier in the region. Moreover, continuous negative MB has brought a peculiar change in the epiglacial morphology in the lower tongue of the glacier as differential debris thickness-induced differential melting has turned the glacier surface into a concave one. This concavity has led to development of a large (10–20 m deep) supraglacial channel which is expanding incessantly. The supraglacial channel is also connected with the snout wall and accelerates terminus disintegration. Given the total thickness of about 30–50 m in the lower glacier tongue, downwasting at its current pace, deepening/widening of supraglacial channel coupled with rapid terminus retreat may lead to the complete vanishing of the lower one km glacier tongue.
The higher concentration of PM10 and PM2.5 in the lower atmosphere is severely harmful for human health and it also makes visibility diminution along with weather and climate modifications. The main objective is to find out the spatiotemporal variation and dispersal of PM10 and PM2.5 along with COVID-19 infection in the dusty city Kolkata. The consecutive two years PM10 and PM2.5 data of different stations have been obtained from State Pollution Control Board, Govt. of West Bengal. Forward trajectory analysis has been done through HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory) model to find the path and direction of air particles. The result showed that the various meteorological or environmental factors (such as temperature, relative humidity, wind, wind speed, pressure and gusty wind) and geographical location regulate the spatiotemporal variation of PM10 and PM2.5. These factors like high temperature with relative humidity and strong wind influence to disperse the particulate matters from north to south direction from city to outside during summer in Kolkata metropolitan city. During summer (both pre and lockdown years), the height of particles is extended up to 1000 m owing to active atmospheric ventilation whereas in winter it is confined within 100 m. The HYSPLIT model clearly specified that the particles dispersed from south, south-west to north and north east direction due to strong wind. The constant magnification of PM10 and PM2.5 in the lower atmosphere leads to greater frequency of COVID-19 infections and deaths. In Kolkata, the one of the crucial reasons of high infection and deaths (COVID-19) is co-morbidity of people.
Soil swelling-related disaster is considered as one of the most devastating geo-hazards in modern history. Hence, proper determination of a soil’s ability to expand is very vital for achieving a secure and safe ground for infrastructures. Accordingly, this study has provided a novel and intelligent approach that enables an improved estimation of swelling by using kernelised machines (Bayesian linear regression (BLR) & bayes point machine (BPM) support vector machine (SVM) and deep-support vector machine (D-SVM)); (multiple linear regressor (REG), logistic regressor (LR) and artificial neural network (ANN)), tree-based algorithms such as decision forest (RDF) & boosted trees (BDT). Also, and for the first time, meta-heuristic classifiers incorporating the techniques of voting (VE) and stacking (SE) were utilised. Different independent scenarios of explanatory features’ combination that influence soil behaviour in swelling were investigated. Preliminary results indicated BLR as possessing the highest amount of deviation from the predictor variable (the actual swell-strain). REG and BLR performed slightly better than ANN while the meta-heuristic learners (VE and SE) produced the best overall performance (greatest R2 value of 0.94 and RMSE of 0.06% exhibited by VE). CEC, plasticity index and moisture content were the features considered to have the highest level of importance. Kernelized binary classifiers (SVM, D-SVM and BPM) gave better accuracy (average accuracy and recall rate of 0.93 and 0.60) compared to ANN, LR and RDF. Sensitivity-driven diagnostic test indicated that the meta-heuristic models’ best performance occurred when ML training was conducted using k-fold validation technique. Finally, it is recommended that the concepts developed herein be deployed during the preliminary phases of a geotechnical or geological site characterisation by using the best performing meta-heuristic models via their background coding resource.
The Spontang Ophiolite complex represents the most complete ophiolite sequence amongst the South Ladakh ophiolites and comprises mantle rocks (depleted harzburgites, dunites and minor lherzolites) as well as crustal rocks (basalt, isotropic gabbros, layered gabbros etc.). In the present study, detailed geochemistry (whole rock as well as mineral chemistry) and Sr-Nd isotopic analyses of thirty-six ultramafic- mafic samples have been attempted to constraint the evolution and petrogenetic history of the Tethyan oceanic crust. Major, trace-element and REE patterns of the peridotites and their minerals indicate that the lherzolites experienced lower degrees of partial melting resembling abyssal peridotites (at higher temperatures, TREE = ∼1216 °C) than the harzburgites (6%–8% versus 15%–17%). Elevated εNd(t) and variable 87Sr/86Sr(t) ratios along with REE patterns suggest that the Spontang mafic rocks display N-MORB affinity with negligible participation of oceanic sediments in their genesis are originated from a depleted upper mantle with little contribution from subduction-related fluids. MORB-type Neotethyan oceanic crust is associated with the earliest phase of subduction (of older Jurassic age) through which a younger intra-oceanic island arc (Spong arc) subsequently developed. Harzburgites REE display typical U-shaped patterns, suggesting that these rocks have been metasomatized by LREE-enriched fluids. On the other side, mafic rocks are characterized by heterogeneous (Nb/La)PM and (Hf/Sm)PM and relatively homogeneous εNd(t), indicating interaction of subduction-related melts with the upper mantle during the initiation of subduction, in Early Cretaceous times.
Discontinuous chains of ultramafic rock bodies form part of the 3800–3700 Ma Isua Supracrustal Belt (ISB), hosted in the Itsaq Gneiss Complex of southwestern Greenland. These bodies are among the world’s oldest outcrops of ultramafic rocks and hence an invaluable geologic record. Ultramafic rocks from Lens B in the northwestern limb of ISB show characteristics of several stages of serpentinization and deserpentinization forming prograde and retrograde mineral assemblages. Ti-rich humite-group minerals such as titanian chondrodite (Ti-Chn) and titanian clinohumite (Ti-Chu) often occur as accessory phases in the metamorphosed ultramafic rocks. The Ti-rich humite minerals are associated with metamorphic olivine. The host olivine is highly forsteritic (Fo96-98) with variable MnO and NiO contents. The concentrations of the rare-earth elements (REE) and high-field strength elements (HFSE) of the metamorphic olivine are higher than typical mantle olivine. The textural and chemical characteristics of the olivine indicate metamorphic origin as a result of deserpentinization of a serpentinized ultramafic protolith rather than primary assemblage reflecting mantle residues from high-degrees of partial melting. The close association of olivine, antigorite and intergrown Ti-Chn and Ti-Chu suggests pressure condition between ∼1.3–2.6 GPa within the antigorite stability field (<700 °C). The overall petrological and geochemical features of Lens B ultramafic body within the Eoarchean ISB indicate that these are allochthonous ultramafic rocks that recorded serpentine dehydration at relatively lower temperature and reached eclogite facies condition during their complex metamorphic history similar to exhumed UHP ultramafic rocks in modern subduction zone channels.
The blockage induced by particle migration and deposition is one of the main reasons for the decrease of reinjection capacity in the porous geothermal reservoir with a low and medium temperature. In this paper, a new drilled geothermal well in Xining basin China is taken as an example to investigate the formation blockage risk due to the movable clay and sand particles in pores. The physical properties of the reservoir rocks were analyzed, a series of pumping and reinjection tests were conducted, and the long-term reinjection performance of the well was predicted by numerical simulation based on the test fitting. The results show that the geothermal reservoir rocks are argillaceous and weakly cemented sandstones with a content of movable clay and sand particles up to 0.18–23.42 wt.%. The well presented a high productivity of 935–2186 m3·d−1 at a pressure difference of 0.7–1.62 MPa in the pumping tests associated with a large amount of clay and sand particles produced out, while in the reinjection test, only a low injectivity of 240–480 m3·d−1 was observed at an injection pressure of 0.2–0.6 MPa with the clay and sand particles near the wellbore move into deep. According to the prediction, under conditions of a blockage risk, the injectivity of the well will start to decline after 100 days of injection, and in the third year, it will decrease by 59.00%–77.09%. The influence of invasion of pretreated suspended particles and scale particles can be neglected. Under conditions of a high blockage risk, the injectivity of the well will decrease significantly in the first 20–30 days, with a decline of 75.39%–78.96%. Generally, the higher the injection pressure or rate, the greater the decrease in injectivity of the well caused by particle blockage. Pump lifting is an effective measure to remove the well blockage which can be used regularly.
The lithofacies classification is essential for oil and gas reservoir exploration and development. The traditional method of lithofacies classification is based on “core calibration logging” and the experience of geologists. This approach has strong subjectivity, low efficiency, and high uncertainty. This uncertainty may be one of the key factors affecting the results of 3D modeling of tight sandstone reservoirs. In recent years, deep learning, which is a cutting-edge artificial intelligence technology, has attracted attention from various fields. However, the study of deep-learning techniques in the field of lithofacies classification has not been sufficient. Therefore, this paper proposes a novel hybrid deep-learning model based on the efficient data feature-extraction ability of convolutional neural networks (CNN) and the excellent ability to describe time-dependent features of long short-term memory networks (LSTM) to conduct lithological facies-classification experiments. The results of a series of experiments show that the hybrid CNN-LSTM model had an average accuracy of 87.3% and the best classification effect compared to the CNN, LSTM or the three commonly used machine learning models (Support vector machine, random forest, and gradient boosting decision tree). In addition, the borderline synthetic minority oversampling technique (BSMOTE) is introduced to address the class-imbalance issue of raw data. The results show that processed data balance can significantly improve the accuracy of lithofacies classification. Beside that, based on the fine lithofacies constraints, the sequential indicator simulation method is used to establish a three-dimensional lithofacies model, which completes the fine description of the spatial distribution of tight sandstone reservoirs in the study area. According to this comprehensive analysis, the proposed CNN-LSTM model, which eliminates class imbalance, can be effectively applied to lithofacies classification, and is expected to improve the reality of the geological model for the tight sandstone reservoirs.
The Earth’s natural pulse electromagnetic field data consists typically of an underlying variation tendency of intensity and irregularities. The change tendency may be related to the occurrence of earthquake disasters. Forecasting of the underlying intensity trend plays an important role in the analysis of data and disaster monitoring. Combining chaos theory and the radial basis function neural network, this paper proposes a forecasting model of the chaotic radial basis function neural network to conduct underlying intensity trend forecasting by the Earth’s natural pulse electromagnetic field signal. The main strategy of this forecasting model is to obtain parameters as the basis for optimizing the radial basis function neural network and to forecast the reconstructed Earth’s natural pulse electromagnetic field data. In verification experiments, we employ the 3 and 6 days’ data of two channels as training samples to forecast the 14 and 21-day Earth’s natural pulse electromagnetic field data respectively. According to the forecasting results and absolute error results, the chaotic radial basis function forecasting model can fit the fluctuation trend of the actual signal strength, effectively reduce the forecasting error compared with the traditional radial basis function model. Hence, this network may be useful for studying the characteristics of the Earth’s natural pulse electromagnetic field signal before a strong earthquake and we hope it can contribute to the electromagnetic anomaly monitoring before the earthquake.
Air pollution by particulate matter (PM) is one of the main threats to human health, particularly in large cities where pollution levels are continually exceeded. According to their source of emission, geography, and local meteorology, the pollutant particles vary in size and composition. These particles are conditioned to the aerodynamic diameter and thus classified as coarse (2.5–10 μm), fine (0.1–2.5 μm), and ultrafine (<0.1 μm), where the degree of toxicity becomes greater for smaller particles. These particles can get into the lungs and translocate into vital organs due to their size, causing significant human health consequences. Besides, PM pollutants have been linked to respiratory conditions, genotoxic, mutagenic, and carcinogenic activity in human beings. This paper presents an overview of emission sources, physicochemical characteristics, collection and measurement methodologies, toxicity, and existing control mechanisms for ultrafine particles (UFPs) in the last fifteen years.
Black carbon (BC) is one of the short-lived air pollutants that contributes significantly to aerosol radiative forcing and global climate change. It is emitted by the incomplete combustion of fossil fuels, biofuels, and biomass. Urban environments are quite complex and thus, the use of mobile jointly with fixed monitoring provides a better understanding of the dynamics of BC distribution in such areas. The present study addresses the measurement of BC concentration using real-time mobile and ambient monitoring in Barranquilla, an industrialized urban area of the Colombian Caribbean. A microaethalometer (MA200) and an aethalometer (AE33) were used for measuring the BC concentration. The absorption Ångström exponent (AAE) values were determined for the study area, for identifying the BC emission sources. The results of the ambient sampling show that vehicle traffic emissions prevail; however, the influence of biomass burning was also observed. The mean ambient BC concentration was found to be 1.04 ± 1.03 μg/m3 and varied between 0.5 and 4.0 μg/m3. From the mobile measurements obtained in real traffic conditions on the road, a much higher average value of 16.1 ± 16.5 μg/m3 was measured. Many parts of the city showed BC concentrations higher than 20 μg/m3. The spatial distribution of BC concentration shows that vehicle emissions and traffic jams, a consequence of road and transport infrastructure, are the factors that most affect the BC concentration. A comparison of results obtained from two aethalometers indicates that the concentrations measured by MA200 are 9% lower than those measured by AE33. The AAE obtained was found to vary between 1.1 and 1.6, indicating vehicular emissions as the most crucial source. In addition, it was observed that the BC concentration on working days was 2.5 times higher than on the weekends in the case of mobile monitoring and 1.5 times higher in the case of ambient monitoring.